Side wall core taking apparatus



Aug. 2, 1960 H. u. GARRETT ETAL 2,947,518

SIDE] WALL CORE TAKING APPARATUS Filed May 1, 1957 3 Sheets-Sheet 1 H y U. Gar/eff Norma/7 F. Brown INVENTORS ffM Aug. 2, 1960 Filed May 1, 1957 H. U. GARRETT ET AL SIDE WALL CORE TAKING APPARATUS SheetsSheet 2 Henry U. 6am e z 2 Norm 0/7 Brow/7 INVENTORS ATTORNEYS Aug. 2, 1960 H. u. GARRETT ET AL 2,947,513

SIDE WALL CORE TAKING APPARATUS Filed May 1, 1957 3 Sheets-Sheet 3 Henry 6/. Garref/ Nor/7700 F. Eran/x7 INVENTGRS ATTORNEYS United States Patent i SIDE WALL CORE TAKING APPARATUS Henry U. Garrett and Norman F. Brown, Longview, Tex., assignors, by mesne assignments, to Henry U. Garrett, Longview, Tex.

Filed May 1, 1957, Ser. No. 656,383

12 Claims. (Cl. 255-14) This invention relates to tools for taking core samples from a well formation and more particularly to tools for taking core samples from the side wall of a well.

Cores are taken from a well wall by driving a tubular core drill into the wall and retracting the drill. Core catchers in the drill latch on to the core. As the core must be broken loose from the well wall and the retracting pull is usually at an angle to the longitudinal axis of the drill, great force must be exerted to retract the drill and core.

In core drills of the type shown in US. Letters Patent to J. R. Yancy et at. No. 2,558,227, wire lines used to retract the core drill are sometimes pulled in two in an attempt to retract a stuck core drill. The size of wire lines which may be used to retract core drills is limited and it would be advantageous to be able to exert a greater retracting force on core drills of this type than is presently possible with wire lines.

This invention provides a hydraulic retractor for drills and is particularly adapted for use with drills of the type shown in the Yancy patent. The retracting force possible with this invention greatly exceeds the force which may be applied by wire line. One factor directly controlling the retracting force is the pressure of mud delivered to the tool through the drill string. As this pressure may be greatly increased by compounding pumps, the retracting force may be increased to any needed value to retract the drill. The retractor does not interfere with continued rotation of the drill, and if necessary, the drill may ream its way back out of the hole in the well wall.

This invention also provides a hydraulic retractor for drills of the type using hydraulic pressure to drive the drill out into a Well wall in which the drill is automatically retracted by raising mud pressure above normal drilling pressure to a predetermined higher pressure.

An object of this invention is to provide a hydraulic retractor for the drill of a side Wall coring apparatus.

Another object is to provide a hydraulic retractor for the drillof a side wall coring apparatus of the type using hydraulic pressure to drive the drill out into a well wall.

Another object is to provide a hydraulic retractor for the drill of a side wall coring apparatus of the type using hydraulic pressure to drive the drill out into the well and which signals the full extension of the drill either by an increase or decrease in resistance to flow of mud.

Another object is to provide a hydraulic retractor for a core drill which utilizes substantially the full differential between pressure in the open hole and within the drill string.

Another object is to provide a retracting means for "a rotary type core drill which may be used while rotation of the drill continues to permit the drill to ream its way back out of the hole in the well wall it necessary. Another object is to provide a hydraulic retracting means for a core drill which will deliver a hammer blow and then exert a tremendous retracting force on the drill.

Other objects, features and advantages of this inven- 2,947,518 Patented Aug. 2, .1960

2 tion will appear from the drawings, the specification, and the claims.

In the drawings wherein there are shown illustrative embodiments of this invention and wherein like reference numerals indicate like parts:

Fig. l is a sectional view through a well bore showing a side wall coring apparatus constructed in accordance with this invention taking a core from a side wall of the hole with the tool shown partly in elevation and partly in longitudinal cross section;

Figs. 2A and 2B are views of a fragment of the too shown in Fig. 1 with the core drill in position to begin taking a core. The views are on an enlarged scale with the tool shown partly in elevation and partly in longitudinal cross section and with Fig. 23 being a continuation of Fig. 2A; Fig. 3 is a view similar to Figs. 2A and 2B with the core drill in its fully extended position and at the moment of shifting of the valve controlling the retractor means but before the retractor begins to retract the core drill;

Fig. 4 is a view similar to Fig. 3 showing the core drill being retracted from the side wall of the hole; and

Fig. 5 is a fragmentary sectional View of the apparatus shown in Fig. 1 on an enlarged scale using a modified form of core drill in which the operator is signaled that the core drill is fully extended by a drop in pressure instead of an increase in pressure as is the case with the core drill shown in Figs. 1 through 4.

Referring first to Fig. 1, the core taking apparatus illustrated is suspended from the drill string 10. The apparatus includes an upper section 11 which is nonrotatably secured to the drill string and a lower section 12 which is rotatably depended from section 11 through a swivel connection shown in dashed outline at 13. The core drill 14 is rotated by the upper section 11 of the apparatus and is directed by a whipstock 15 in the lower section 12 into the side wall of a well. The lower section 12 is provided with radially extending ribs 16 which know that the core drill is fully extended by a pressure signal at the slush pump and will raise the pressure in the drill string to operate the retract-or mechanism. When the pressure within the drill string reaches a predetermined value, the valve indicated generally at 19 will be shifted to vent the upper side of the retractor mechanism to the open hole. When this occurs, the diiferential in pressure between the open hole and the pressure within the drill string will be exerted across the retractor mechanism in a direction to drive the core barrel upwardly and retract the core barrel from the side wall of the well.

Reference is now made to Figs. 2A and 2B wherein the details of the mechanism for retracting the core drill are shown. The body of the tool includes a splined driving head 21 at the upper end of the tool. A sleeve valve housing 22 is depended from the head 21 and an outer casing 23 is in turn depended from the housing 22. A mud seal housing 24 interconnects the outer casing with the upper end 25 of the swivel 13. All of these elements of the housing are annular members providing a bore through the housing to accommodate the various elements of the retracting mechanism. These elements are in turn preferably annular in configuration to provide a bore through the retracting mechanism and the housing 7 through which the core drill 14 is extended.

The core drill 14 is provided at its upper end with a key 26 which is urged by springs 27 radially'outward so'asto engage the splines 21a of the spline driving head 21. Thus, by rotation of the drill string, rotary move me'fitwill be imparted to the-core drill.

To provide a'hydraulic drive for the core drill, there isprovided a core barrel seal 28 in the mud seal housing 24"( Fig. 2B) which seals between the mud seal housing 'a'ndthe core drill. Thus, fluid pressure within the drill "the core drill "14 and thence down to the cutting tool 31 (see Fig. l) to lubricate the cutting tool and-remove cuttings from the hole. The holes 29 are adequate to provide for circulation but are sized to permit the operator to maintain the desired pressure drop across the core drillto urge the core drill into the formation.

I When the core drill is fully extended the holes 29 will bewithin the core barrel'seal28 as showni-n Fig. 3.

When this occurs, theresistance to flow of-mud pressure will increase and signal the operator that the core-drill has been fully extended. To avoid damage to the mud pump or popping of relief valves, a small diameter inlet '32 is provided in the upper end of the core drill so that some circulation will continue through the tool at all times. This small amount of circulation will prevent a rapid excessive buildup of pressure on the pumps and also will continue mud circulation in the well which is highly desirable.

When the core drill is fully extended astop provided by sub 17 in the core drill is engagedby the retractor means 18.

The retractor means 18 providesa fluid'responsive means for driving the sub 17 and hence the entire core drill upwardly to withdraw it from the side wall of the hole. The retractor means illustrated includes a retractor piston 33 which has a plurality of radially inwardly projecting ribs 34 which engage the stop provided by the sub 17. These ribs provide space through the .re-

tractor piston for fluid to flow and reach holes-29 after the holes 29 are below the piston 33 and before they reach the core barrel seal 28.

A sliding seal is provided between the retractor piston and a cylinder liner 35-by suit-able packing 36 held on the piston by a piston packing end ring 37 and a snap ring 38. Upwardly extending from the piston 33- there is a retractor piston tube 39 which moves with the piston 33. A sliding seal is provided between the tube 39 and a cylinder head 41 by suitable packing 42. The packing 42 is held in place on the cylinder .head by a suitable packing ring 43 and snap ring 44.

The retractor piston 33, retractor tube-39, cy1inder liner 35 and cylinder head 41 provide a variable volume chamber 45. If this chamber be subjected to drill string pressure, which will also be present on the underside of piston '33, the piston 33 will merely float in the cylinder fliner 35 during normal coring operations. Then if the variable Volume chamber 45 be vented to the open hole,

a differential will be provided across retractor piston 33 which will drive the piston upwardly and retract the coring drill from the side wall of the hole.

Fluid pressure from the drill string is conducted to the chamber 45 through a ring of ports 46 receiving fluid from an annular gathering ring 47 in the inner wall of the sleeve valve housing .22 (Fig. 2A). Gathering ring 47 receives fluid via annuli 47a and 52a. Fluid is conducted from the ports 46 through the annulus between the inner tube 48 and the outer casing 23 to the annulus between the cylinder liner 35 and the outer casing 23. Grooves 49 in the cylinder head 41 permit fluid to freely pass the cylinder head. Fluid communication is provided between the variable volume chamber 45 and the annulus between the cylinder liner 35 and outer casing 23 by a plurality of holes 51 in the cylinder liner.

Through the passageway traced in the last paragraph fluid pressure within the drill stringis maintained on the top of the retractor piston 33 and opposes pressure on the bottom of the retr-actor piston 33. If 'means be provided for closing 01f fluid communication between the ports 46 and the bore through the housing and establishing communication between the ports 46 and the exterior of the housing, that is, the open hole, then drill string pressure can be removed from the chamber 45'and a-difierential equal to the drill string pressure'at the retractor-piston will be exerted across the piston in a direction to raise the retractor piston.

In the illustrated embodiment, the piston valve v19 (Fig. 2A) provides a means for alternately connecting the ports 46 with the interior of the housing-and with-the open hole. The piston-valve includes a sleeve valve piston 52 having mounted thereon spaced packing elements 53 and 54. These packing elements provide a slidingseal between the piston-valve 19 and the inner wall of sleeve valve housing 22. It will be noted that thecylinder wall sections provided within the sleeve valve housing 22 for engaging the sliding seals 53 and 54 are of slightly diflf'erent diameter. The space 55 defined by these sliding seals is connected with the exterior of the housing througha plurality of ports, one of which is shown at 56. The space'between'the two sliding seals is always in communication with the open hole. Asthe opposite ends of the two sliding seals 53 and 54 are exposed to drill string pressure and the end of the pistonvalve carrying sliding seal 54 has a pressure'responsive surface of slightly. larger area-than the end of the pistonvalve carrying sliding seal 53, there will be'provided a pressure responsive area on the piston-valve which tends to urgethe valve longitudinally of the tool with a'force determined by the pressure within the drill string.

During core taking-operations, seal 53 connects the ports 46 with the interior of inner tube 48 to pressurize the top of-retractor vl8. When the piston-valve is shifted by an increase'in pressure, seal 53 passes overfports 46 and connects these ports with ports 56 leading to the exterior of the mill to vent the pressure on the top of retractor 18 to the open hole.

To prevent shifting of the valve by theaction ofpres- 4 sure within the drill string on the piston-valve, there is provided detent' means which retains the piston-valve-until a predetermined drill string pressure is exerted on piston-valve 19. The detent means illustrated includes a spring 57 and a detent ring 58. The spring .57 is compressed between a lower spring seat 59 weldedforotherwise suitably secured within the inner tube 48 and a spring seat ring 61 on the adjacent end of valve 19. The spring 57 also functions to return the valve to the-position shownin Fig. 2A- afterit has been shifted and drill string pressure reduced. The detent ring 58 is held between a detent-backup ring- 62 and a detent retaining nut 63. The detent backupring 62 is held in place by a snap ring 64. Then-ht 63 is threadedly received on the sleeve valve piston 52. A locking pin 65 locks the nut in nonrotative position relative to detent ring 58. Asnap ring 66 retains the locking pin inplace.

The abut-ting surfaces 63a and 58a of the detent retaining nut 63 and-the detent ring'58, respectively, are inclined at acute angles to the longitudinal axis of 'thetool to provide wedge surfaces which tend to contract the detentring as the piston-valve moves .againstspring 57. .Surface 58bof the detent ring rests on a surface 67 proposition. wedge surfaces which assist in contracting the wedge motion. provide a hammer blow.

'in the rotary table for rotation in the usual manner. this time the apparatus will be as illustrated in Figs. 2A and 2B.

"vided by an internal annular shoulder within the sleeve valve housing 22 when the piston-valve is in the Fig. 2A These surfaces are also inclined to provide ring.

The detent ring 58 is a split ring which, when sufiicient force is exerted on the sleeve valve 19, will be forced off of shoulder 67 to permit pressure shifting of the sleeve valve. The force necessary to contract the detent ring and to overcome the resistance to downward movement of the piston-valve oiiered by spring 57 will be the predetermined force necessary to pressure shift the piston-valve and establish communication between the ports 46 and the ports 56 which lead to the open hole.

'In the absence of the detent ring, pressure building up within the drill string would force the piston-valve '19' to slowly move downward to a position at which it would cover the ports 46 while not uncovering the ports 56. This condition would occur before the predetermined pressure for operating the piston-valve when the detent ring 58 is employed. Thus, the maximum work ing pressure available for normal drilling would have to'be reduced or the predetermined pressure at which the valve would open would have to be increased to avoid the occurrence of a diiferential across the retracting piston 33 during normal drilling operations which would oppose the force of fluid pressure urging the core drill out into the well. As the eflective area of the retractor piston is much larger than the effective pressure responsive area of the core drill, a relatively small differential across the retractor piston would be objectionable because it would tend to reduce the force with which the core bit is urged into the formation.

The detent ring provides a snap action for the pistonvalve 19 which will drive the piston-valve down to a position at which the ports 46 will be completely uncovered and their full area will be available for effective bleeding of pressure from the variable volume chamber 45. As the fluid within the variable volume chamber 45 will be a liquid, only a small amount need be exhausted from the chamber to equalize pressure within the chamber 45 with the open hole and, therefore, a very rapid build-up in differential across the retractor piston 33 will occur. This will provide a hammer action which, even with the coring tool in fully extended position, will be effective on the cutting end of the coring tool. The hammer blow is permitted by the slight play in the swivel joints 68 and 69 in the coring drill and by straightening out of the angles provided by the swivel joints when the core bit begins its upward movement. Also, the entire lower portion 12 of the assembly will tend to move over toward the portion of the side wall of the well in which a hole has been cut by the coring tool to provide additional lost While this lost motion will be small, it will It is believed that operation of the tool is apparent from the above detailed explanation but it will be sum- 'marized here for convenience.

The core taking assembly illustrated minus the core drill is made up on the lower end of a drill string and run into the hole to the desired depth. The core drill 1 4 is then run in the hole on a wire line until the driving key 26 engages the spline section 21. The string is then suspended from the kelly At Fluid pressure from the slush pumps is applied in the usual manner within the drill string to urge the coring bit out into the formation while at the same time the string is rotated by the rotary table. Pressure on the coring bit forces it against the side wall and the blades 16 section of the tool. Primary mud circulation is provided through the" inlets 29 into the hollow core "drill and passes through the drill to the cutting end 31 of the tool where it washes cuttings from the hole and lubricates the tool.

When the core drill has been moved down in the assembly a predetermined length, the holes 29 pass into the core barrel seal 28 and prevent flow of mud into the core barrel through these ports. While some flow still continues through the bleed inlet 32, the resistance to flow of mud is raised a considerable amount to signal the operator that the core bit has been fully extended. This condition is illustrated in Fig. 1. At this time mud presure is increased to a value greater than the predetermined pressure at which the piston-valve 19 will shift and this pressure will cause the detent ring 58 to be contracted and the piston valve to shift to its down position. This will place the ports 46 and 56 in communication with each other and drill string pressure which has been conducted to the variable volume chamber 45 through the entryway provided by ports '46 during drilling operations will now be vented to the open hole through ports 56. This condition is shown in Fig. 3. When this occurs the drill string pressure will be exerted across the retractor piston 33 in an upward direction and the piston will move upwardly engaging the stop 17 on the core drill to raise the core drill to its retracted position. The retractor piston will, of course, move upwardly until it engages the cylinder head 41. Fig. 4 illustrates the core drill being raised.

In the event the core barrel sticks in the formation and does not come free, then the rotary table may be started up again, if it has been stopped, and the combined upward force and rotary force on the core barrel will permit the core barrel to ream its way back out of the hole in the side Wall of the formation.

As an alternative, the pressure within the drill string may be increased and decreased across the predetermined pressure at which the piston-valve 19 is operated to alternately connect the variable volume chamber 45 with the pressure within the drill string and with the open hole pressure to apply successive hammer blows and pulls on the coring tool.

It is noted that when the core barrel reaches a partly retracted position the ports 29 will be retracted from the core barrel seal 28 and there will be a drop in resistance to flow of drilling mud. This will indicate to the operator that he has broken the core loose and has obtained at least initial movement of the core bit toward retracted position.

After the core bit has been retracted, the string is lifted to place slips in the rotary table about the top section of the drill string and the kelly may then be removed. A wire line is run in the hole to engage the core barrel and bring it to the surface. At this time the entire assembly may be removed from the hole or additional core bits may be run and the operation repeated successively as many times as is desired to obtain the desired cores from the well.

Fig. 5 illustrates a modified form of core drill in which mud circulation is provided by introducing mud into the upper end of the core drill through inlets 71. A plurality of ports 72 are provided in the core bit at a point below the stop sub 17 and during normal coring some fluid will also enter the core barrel through these holes. As these holes pass through the core barrel seal 28, they permit fluid entering through the primary inlet 71 into the core barrel to exhaust through. the holes 72 into the swivel joint and thence into the open hole. In this manner resistance to flow of mud is reduced and this reduction in presssure signals the operator at the surface that the core bit is fully extended. In this form of tool pressure drop across the core drill is provided for downstream of the holes 72. See the Yancy patent. Thereafter, the operator increases pressure Within the drill .string in the same manner as heretofore explained to operate the sleeve valve 19 and raise the retracting piston 33 .to -retractthe core bit from the wall ofthe well. 'In- .asmuch as mud is fiowing into the open hole through the ports .72, it will beappreoiated-that a greater pump capacity will be required to obtain the same pressure conditions "as are possible in the Figs. 1 through 4 illustrated embodiment and, therefore, it is preferred to use the form of core bit which signals full extension of the core .bit by an increase in pressure rather than a decrease in pressure.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set 'forth, together with other advantages which .are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. Thistis contemplated by and is within the scope of the claims.

Asmany possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted asillustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. Aside wall coring tool comprising, a body having a passageway therein adapted to be run on a drill string, a ;piston' in said body, retractor means carried by the piston for retracting a side wall core drill from the wall .of a well into the passageway, a chamber in said body,

said piston exposed on one side to the passageway and onthe other side to the chamber, port means for fluidly connecting the chamber with the passageway and with thezextenior of the'body, valve means operable to con- .trol'flow through the port means so that said chamber is alternately connected with the passageway and the exterior of the body, and means for operating the valve meansin response to predetermined pressure conditions in the a passageway.

2. A side wall coring tool comprising, a body having atpassageway therein adapted to be run on a drill string, a piston in said body, retractor means carried by the piston for retracting a side wall core drill from the wall .of a well into the passageway, a chamber in said body,

is alternately connected with the passageway and the exterior of the body, and piston means for shifting the valve means from a position connecting the chamber with the passageway to a position connecting the chamber with the exterior of the body in response to a predetermined high pressure in the fluid passageway.

3. A side wall coring tool comprising, a body having a passageway therein adapted to be run on a drill string, a piston in said body, retractor means carried by the piston for retracting a side wall core drill from the Wall of awell into the passageway, a chamber in said body, said piston exposed on one side to the passageway and onthe other side to the chamber, port means for fluidly connecting-the chamber'with the passageway and with the exterior of'the body, valve means operable to control flow-through the port means so that said chamber is alternately connected with the passageway and the exterior of the body, piston means connected to the valve meansto shift the same from a position connecting theehamber with the passageway to a position connecting the chamber with the exterior of the body in response to a predetermined high pressure in the passageway, and detent means holding the piston means in unshifted positionuntil said predetermined pressure conditionsexist in the passageway.

V 18 4. A side wall coring tool compnisingabody having a -passageway thereinadaptedto be run on adrill string,

-a piston in said body, retractor means carried by the piston for retracting a side wall core 'drill 'from the wall of a well into the passageway, a chamber in said body, said piston exposed 'on one side to the passageway and on theother side to the chamber, :a-combination pistonslide valve having spaced seals engaging spaced cylinder wall sections of the body, said piston-slide valve having opposed pressure responsive surfaces of different area exposed to pressure in the passageway, port means interconnecting the space defined by said seals with the exterior of the body, resilient means urging the pistonvalve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface, and port means interconnecting the chamber .with one of the cylinder wall sections at a point outsideof said spaced seals when the piston-valve is in its resilient means urged position and between said seals whenthe piston-valve is shifted by pressure in the passageway against thev resilient means.

5. A side wall coring tool comprising, a body having a passageway therein adapted to be run on a drill string, a piston in said body, retractor means carried by "the piston for retracting a side wall core drill from the wall of a well into the passageway, a chamber insaidbody, said piston exposed on one side to the passageway and on the other side to the chamber, a combination pistonslide valve having spaced seals engaging spaced cylinder wall sections of the body, said piston-slide valve having opposed pressure responsive surfaces of different area exposed to pressure in the passageway, port means interconnecting the space defined by said seals with the exterior of the body, detent means including resilient means urging the piston-valve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface preventing pressure shifting of the piston-valve until pressure in the passageway reaches a predetermined high pressure, and port means interconnecting the chamber with one of the cylinder wall sections at a point outside of said spaced seals when the piston-valve is in its resilient means urged position and between said seals when the piston-valve is shifted by pressure in the passageway against the resilient means.

6. A side wall coring tool comprising, a body having a passageway therein adapted to be run on a drill string, a piston in said body, retractor means carried by the piston for retracting a side wall core drill from the Wall of a well into the passageway, a chamber in said body, said piston exposed on one side to the passageway and on the other side to the chamber, a combination sleevepiston-slide valve having spaced annular seals engaging longitudinally spaced cylinder Wall body sections of different diameter and providing opposed pressure responsive surfaces on the piston-valve of different area exposed to pressure in the passageway, port means interconnecting the space defined by said seals with the exterior of the body, resilient means urging the pistonvalve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface, and port means interconnecting the chamber with the smaller diameter cylinder wall section at a point outside of the spaced seals when the piston-valve is in its resilient means urged position and between said seals when the piston-valve is shifted by pressure in the passageway against the resilient means.

7. A side wall coring tool comprising, a body having a passageway therein adapted to be run on a drill string, a piston in said body, retractor means carried by the piston for retracting a side wall core drill from the wall of a well into the passageway, a chamber in said body, said piston exposed on one side to the passageway and on the other side to the chamber, a combinationsleevepiston-slide valve having spaced annular seals engaging longitudinally spaced cylinder wall body sections of different diameter and providing opposed pressure responsive surfaces on the piston-valve of difierent area exposed to pressure in the passageway, port means interconnecting the space defined by said seals with the exterior of the body, detent means including resilient means urging the piston-valve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface and preventing pressure shifting of the piston-valve until pressure in the passageway reaches a predetermined high pressure, and port means interconnecting the chamber with the smaller diameter cylinder wall section at a point outside of the spaced seals when the pistonvalve is in its resilient means urged position and between said seals when the piston-valve is shifted by pressure in the passageway against the resilient means.

8. A side wall coring tool comprising, an elongate body having a longitudinal bore therein adapted to be run on a drill string, a side wall core drill adapted to be received in the bore of said body and to be directed into the side wall of a well to take a core, a stop on the core dnill, retractor means in the body and engageable with the stop on the core drill to retract the core drill from the wall of a well into the bore of the body, said retractor means including a piston mounted in said body, a chamber in said body, said piston exposed on one side to the bore through the body and on the other side to the chamber, port means for fluidly connecting the chamber with the bore and with the exterior of the body, valve means operable to control ilow through the port means so that said chamber is alternately connected with the bore through the body and the exterior of the body, and means for operating the valve means in response to predetermined pressure conditions in the bore.

9. A side wall coring tool comprising, an elongate body having a longitudinal bore therein adapted to be run on a drill string, a side wall core drill adapted to be received in the bore of said body and to be directed into the side wall of a well to take a core, a stop on the core drill, retractor means in the body and engageable with the stop on the core drill to retract the core drill from the wall of a Well into the bore of the body, said retractor means including a piston mounted in said body, a chamber in said body, said piston exposed on one side to the bore through the body and on the other side to the chamber, port means for fluidly connecting the chamber with the bore and with the exterior of the body, valve means operable to control flow through the port means so that said chamber is alternately connected with the bore through the body and the exterior of the body, and piston means for shifting the valve means from a position connecting the chamber with the bore of the body to a position connecting the chamber with the exterior of the body in response to a predetermined high pressure in the bore of the body.

10. A side wall coring tool comprising, an elongate body having a longitudinal bore therein adapted to be run on a drill string, a side wall core drill adapted to be received in the bore of said body and to be directed into the side wall of a well to take a core, a stop on the core drill, retractor means in the body and engageable with the stop on the core drill to retract the core drill from the wall of a well into bore of the body, said retractor means including a piston mounted in said body, a chamber in said body, said piston exposed on one side to the bore through the body and on the other side to the chamber, port means for fluidly connecting the chamber with the bore and with the exterior of the body, valve means operable to control flow through the port means so that said chamber is alternately connected with the bore through the body and the exterior of the body, piston means for shifting the valve means from a position connecting the chamber with the bore of the body to a position connecting the chamber with the exterior of the body in response to a predetermined high pressure in the bore of the body, and detent means hold ing the piston means in unshifted position until said predetermined pressure condition exists in the bore.

11. A side wall coring tool comprising, an elongate body having a longitudinal bore therein adapted to be run on a drill string, a side wall core drill adapted to be received in the bore of said body and to be directed into the side wall of a well to take a core, a stop on the core drill, retractor means in the body and engageable with the stop on the core drill to retract the core drill from the wall of a well into the bore of the body, said retractor means including a piston mounted in said body, a chamber in said body, said piston exposed on one side to the bore through the body and on the other side to the chamber, a combination piston-slide valve having spaced seals engaging spaced cylinder wall sections of the body, said piston-valve having opposed pressure responsive surfaces of different area exposed to pressure in the bore, port means interconnecting the space defined by said seals with the exterior of the body, resilient means urging the piston-valve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface, and port means interconnecting the chamber with one of the cylinder walls at a point outside of said spaced seals when the piston-valve is in its resilient means urged position and between said seals when the piston-valve is shifted by pressure in the bore of the body against the resilient means.

12. A side wall coring tool comprising, an elongate body having a longitudinal bore therein adapted to be run on a drill string, a side wall core drill adapted to be received in the bore of said body and to be directed into the side wall of a well to take a core, a stop on the core drill, retractor means in the body and engageable with the stop on the core drill to retract the core drill from the wall of a Well into the bore of the body, said retractor means including a piston mounted in said body, a chamber in said body, said piston exposed on one side to the bore through the body and on the other side to the chamber, a combination piston-slide valve having spaced seals engaging spaced cylinder wall sections of the body, said piston-valve having opposed pressure responsive surfaces of different area exposed to pressure in the bore, port means interconnecting the space defined by said seals with the exterior of the body, detent means including resilient means urging the piston-valve in a direction from the smaller pressure responsive surface toward the larger pressure responsive surface and preventing pressure shifting of the piston-valve until the pressure in the bore of the body reaches a predetermined high pressure, and port means interconnecting the chamber with one of the cylinder walls at a point outside of said spaced seals when the piston-valve is in its resilient means urged position and between said seals when the piston-valve is shifted by pressure in the bore of the body against the resilient means.

References Cited in the file of this patent UNITED STATES PATENTS 2,221,392 Baker Nov. 12, 1940 2,277,989 Kinnear Mar. 31, 1942 2,327,023 Danner Aug. 17, 1943 2,558,227 Yancy June 26, 1951 2,747,841 Adamson May 29, 1956 

